Composite sandwich panels are materials used with increasing frequency in various applications due to their excellent mechanical properties in light of their low mass.
A composite sandwich panel generally comprises a central layer forming a web that is gripped, sandwiched, between an inner skin and an outer skin made from a composite material, i.e. each made up of one or several fibrous plies pre-impregnated with resin that is then polymerized during a curing step.
Other methods use dry fibrous plies, i.e. not pre-impregnated with resin, the resin being applied later during a curing step during which it is forced by suction to spread between the fibrous plies.
Of course, a composite sandwich panel can also comprise several central layers, of the same type or different types, the central layers themselves being able to be separated by a layer of composite material.
The central layers can, for example, be of the cellular, balsa, or foam type, or can comprise one or several fusible inserts.
The composite sandwich panels use a honeycomb, balsa or foam, web, for example, helping reduce the mass of the objects while preserving or even increasing their mechanical properties.
The inner and/or outer skins can have particular finishes depending on the final application of the panel. An example of a finishing could be piercings through the inner skin in the case of an acoustic panel. Other examples in particular comprise conductive skins, sealing skins, etc . . .
One of the fields where the use of composite sandwich panels is particularly developed is in the aeronautics field.
Such panels are in particular used for floors, partitions, wing panels, etc.
Indeed, many panels, initially made from aluminum, were able to be replaced by composite sandwich panels, in particular comprising a web with a cellular structure of the Nomex, Kevlar or metal type, for example, much lighter and ensuring excellent mechanical properties, which allows significant lightening of airplanes and, as a result, causes decreased fuel consumption.
However, the curved zones in such panels are generally more fragile and must be reinforced, as these curved zones constitute stress concentration zones due to the bending of the piece. To do that, fittings or heavy reinforcements are used made from monolithic fabrics.
As a result, there is a need for a solution making it possible to effectively reinforce curved zones of a composite sandwich panel without excessively affecting the mass of said panel.